APOLLO LUNAR SURFACE EXPERIMENTS PACKAGE AND ASSOCIATED LUNAR SURFACE EQUIPMENT

Difficulty in penetrating the surface to the desired depth with the bore stems

The bore stem sections are made of a fiberglass and boron filament laminate, chosen for its optimum thermal characteristics as a casing for the heat flow experiment probe. The sections are approximately 21 inches long with tapered male and female joints. One-inch double-thread spiral lead flutes are provided on the exterior surface to transport the soil chips from the drilled hole to the surface. The depth of the flutes is 0.050 inch for about 18 inches, but the flutes almost disappear at the joint area where the wall thickness must follow the taper of the joint ( fig. 14-41). As a result, the volume of chip flow to the surface is slowed considerably in looser soil formations, and stalled by the packing of the chips in high-density formations.

In order to reduce the time required, prevent damage to bore stems, and increase the probability of attaining the full depth, the following modifications and corrective actions are being implemented:

The bore stem joints will be changed from boron/fiberglass tapered joints to threaded titanium inserts which provide continuous flutes as do the core stems. The thread configuration also provides a more positive connection, precluding inadvertent separation of the joint in the hole.

The length of the first (bottom) bore stem section will be increased so that the 43-inch probe for the heat flow experiment is housed entirely in the boron/fiberglass material and the titanium joint is not in the probe region.

The length of the remaining sections will be increased by a small amount, which will reduce the number of joints for the crew to mate as well as keep the titanium away from the experiment thermocouples.

Crew training will include boring and coring experience with a soil model typical of the Hadley Rille soil characteristics as well as models of less dense soil.

This anomaly is closed.

Difficulty in releasing bore stems from drill adapter

In the bore stem drilling position, the key blocks are restrained inside, and the spindle drives against the shoulder of the adapter outer shell ( fig. 14-42). The operational sequence to release the bore stem from the adapter includes the following steps:

With the bore stem held stationary, the power head is rotated by hand 90 degrees counterclockwise. This moves the spindle and adapter shoulder about 1/4-inch apart and releases the spring-loaded key blocks outward.

With the key blocks in the outward position, pulsing the power head transfers power from the spindle through the key blocks to the collet shoulder, thus moving the collet about 1/4-inch, and releasing the bore stem.

In development ground tests, the soil friction usually kept the bore stem from turning in this operation. When there was insufficient friction from the soil, the bore stem was grasped with the gloved hand. On Apollo 15, the soil did not hold the bore stem, and the core-stem wrench was used to hold the bore stems for this operation.

The single-purpose core stem wrench is fitted to the 0.983-inch- diameter titanium core stem, but the 1.088-inch throat will admit the 1.075inch-diameter bore stem. The softer bore stem (boron-fiberglass laminate) can be deformed and present some difficulty in wrench removal, with possible damage to the bore stem. A wrench to fit both bore and core stems will be provided.

The change of the bore stem joint, discussed in the previous anomaly, will result in the elimination of the present bore stem drill adapter. The bore stem will thread into the power head spindle adapter in the same manner as the core stems on Apollo 15 and a spindle thread reducer will be provided to fit the core stems. In addition, the training models and procedures will by updated to reflect equipment changes.

This anomaly is closed.

Bore stem damage near the first joint

The probe would not go to the bottom plug of the bottom bore stem in hole 2, but stopped at a point about 6 inches above the first joint. Examination of photographs and heat flow probe data indicate that, near the end of the bore stem drilling operation, the first joint was separated when the drill and drill string were moved vertically (up and down) in an attempt to improve the drill penetration rate. Easier penetration (for approximately 6 inches) was reported by the crew, but it resulted from the bottom of the second section apparently performing more in a coring manner ( fig. 14-43) with the lunar soil entering the second section of the bore stem.

The change from boron/fiberglass to threaded titanium in the bore stem joint will prevent a repetition of such a separation.

This anomaly is closed.

Difficulty in core stem removal from the drilled hole in the lunar surface

Friction of the compacted soil in the drill flutes can build up substantial forces against core stem removal in a deep hole in some soil formations. This was illustrated in premission and drill development experiences.

Interference from the compacted material in the drill flutes can be reduced and core stem removal eased by pulsing the power head when at the bottom of the hole without upward and downward motion of the drill stem. Ground tests have indicated that the best results are obtained when the power head is pulsed just before the power head is removed to add each core stem section. The tendency to auger, as reported by the crew, is also reduced by pulsing the power head before each new core stem is added.

To assure maximum core return and minimum core disturbance for this mission, and without having the benefit of some of the experience from later ground tests, the crew did not pulse the power head. In addition, the core stem string was left in the ground for several hours before the crew returned for its final removal. The core stem string was removed with considerable physical effort, but a very complete core was recovered.

A mechanical assist (modified jacking mechanism) will be mounted on the treadle for easier core removal from difficult formations. Training and procedural changes will be implemented so that the drill motor will be pulsed before the addition of each core stem.

This anomaly is closed.

14.4-1.5 Difficulty in separation of core stem sections

The sections of the core stem string could not be separated using the vise and wrench because the vise had been mounted on the pallet backward. The six section core stem string was removed from the core hole as a single unit and brought to the vise on the lunar roving vehicle. Three sections were separated individually with hand friction on one side of the joint and the wrench on the other side. The remaining three sections were returned to the earth in one piece.

The configuration of the core stem vise is the same as that of the core stem wrench head. The vise is mounted on a bracket on the lunar roving vehicle aft chassis pallet, located on the right hand side of the vehicle. The core stem wrench head is similar to the conventional pipe wrench head, with one fixed jaw and one pivoted jaw. The throat width is not adjustable and is designed to fit the outside diameter of the core stem.

As mounted, the vise would hold the core stem so that the joint could be tightened by rotating the wrench on the adjoining section. However, the vise would not hold in the opposite direction so that the joint could be loosened and separated ( fig. 14-44). Working on the inboard side of the vise, the core stem could have been held properly for loosening; however, there is insufficient clearance on the inboard side of the vise for wrench rotation, and the distance to the other side of the lunar roving vehicle is greater than the length of a core stem section.

The installation drawing of the vise was in error and has been corrected to assure correct orientation of the vise for Apollo 16. The training vise was installed backward from the erroneous drawing, but correct for loosening the stems.

This anomaly is closed.

14.4.2Central Station Rear Curtain Retainer Removal Lanyard Broke

To remove the retainer for the central station rear curtain, added for Apollo 15, it was necessary to remove two retaining pins ( fig.14-45). The two pins, a universal handling tool fitting, and the curtain retainer are joined by a three-section lanyard. When the universal handling tool was inserted in the fitting and raised to remove the first pin, that section of the lanyard broke. When an effort was made to remove both pins simultaneously by inserting the handle under the lanyard joining the two pins, that part of the lanyard broke. The pins and retainer were then removed by hand.

The Dacron lanyard is being changed from a 50-pound test rated material to a 180-pound test rated material with acceptance pull tests being increased to 20 pounds for the entire system.

This anomaly is closed.

14.4.3Intermittent Lock of Universal Handling Tool In Suprathermal Ion Detector Fitting

While carrying the suprathermal ion detector experiment from the subpallet to the emplacement site, the experiment fell off the universal handling tool at least twice. The experiment sustained no visible damage and has been operating satisfactorily.

The universal handling tool fitting on this experiment is in the highest location above the lunar surface of any of the fittings and presents an awkward position of the tool for insertion, locking, and maintaining lock in the fitting ( fig. 14-46).

Corrective action includes training procedures to avoid inadvertent tool-release triggering because of the position of the tool. There are no present plans for the suprathermal ion detector experiment to be carried on future missions, and no other scheduled experiments have a similarly located fitting.

This anomaly is closed

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